Alfresco web-client-config-custom.xml override for guest in Explorer

Question

Hi All i want to make some customization for alfresco web client "Explorer" and i want to make this change only for guest user for example i want to make the landing page of the guest is 'guesthome' i did this by adding to web-client-config-custom.xml

<config>
  <client>

     <!-- The default location to display when the browse screen is first shown -->
     <!-- This value should be one of 'myalfresco', 'userhome', 'companyhome' or 'guesthome' -->
     <initial-location>guesthome</initial-location>
  </client>

but the changes apply to every user how i can make this change available only for the guest user ? I user Alfresco Version :Community - v4.3.0 (r56867) any help please